Levers, pedals, etc. in various automotive and other types of vehicles are input devices operable by human operators or drivers, and, generally, as any one of these input devices is operated by the driver, a certain reaction force is imparted to a hand or foot of the driver through the input device. There has been known a technique that positively generates such a reaction force in response to driver's operation of the lever or pedal, i.e. that allows the lever or pedal to function not only as an input device but also as an output device. Devices using such a technique are called “haptic devices”, one example of which is known from Japanese Patent Laid-Open Publication No. 2001-105926 (JP-A-2001-105926) disclosing a vehicular operation apparatus provided with a haptic device.
FIG. 5 shows the vehicular operation apparatus disclosed in the above-mentioned No. 2001-105926 publication. This vehicular operation apparatus includes a pedal 101 connected via an actuator shaft 102 to a stroke simulator 103. With a stroke sensor 104 provided on the actuator shaft 102, the stroke simulator 103 generates and imparts a reaction force to the pedal 101 in accordance with a stroke of the pedal 101. The stroke sensor 104 is operatively connected via an ECU 105 to a throttle device 106, and the ECU 105 supplies the throttle device 106 with an instruction signal such that the throttle opening is varied in accordance with a detected pedal stroke.
In order to allow kickdown of an automatic transmission to be performed in the vehicle by the driver stepping on or depressing the pedal 101 rapidly and deeply for rapid acceleration, there may be provided a kickdown switch 109 rearwardly of the pedal 101 for generating a kickdown signal. Namely, once the pedal 101 is depressed to a predetermined stroke position, the kickdown switch 109 is turned on to generate an ON signal, and the instructed kickdown of the automatic transmission is executed in response to the ON signal from the switch 109.
With the conventional devices using the haptic technique, however, the driver would feel uncomfortable when returning the pedal 10 from a depressed position in a predetermined reaction-force increasing control region where control is performed to increase the pedal reaction force in accordance with increase in the depression amount of the pedal, because the stroke simulator 103 generates the pedal reaction force in accordance with a stroke of the pedal.